QEMU-user doesn't report HWCAP2_MTE

[Vitaly Buka]

Reproducible on ffa090bc56e73e287a63261e70ac02c0970be61a

Host Debian 5.10.24 x86_64 GNU

Configured with "configure --disable-system --enable-linux-user --static"

This one works and prints "OK" as expected:
clang tests/tcg/aarch64/mte-3.c -target aarch64-linux-gnu -fsanitize=memtag -march=armv8+memtag
qemu-aarch64 --cpu max -L /usr/aarch64-linux-gnu ./a.out && echo OK

This one fails and print "0":
cat mytest.c
#include <stdio.h>
#include <sys/auxv.h>

#ifndef HWCAP2_MTE
#define HWCAP2_MTE (1 << 18)
#endif

int main(int ac, char **av)
{
    printf("%d\n", (int)(getauxval(AT_HWCAP2) & HWCAP2_MTE));
}

clang mytest.c -target aarch64-linux-gnu -fsanitize=memtag -march=armv8+memtag
qemu-aarch64 --cpu max -L /usr/aarch64-linux-gnu ./a.out

[Vitaly Buka (vitalybuka)]

Actually if we make it like this:

#include <stdio.h>
#include <sys/auxv.h>

int main(int ac, char **av)
{
    for (int i = 0; i < 32; ++i)
        if ((int)(getauxval(AT_HWCAP2) & (1 << i)))
            printf("%d\n", i);
}

clang mytest.c -target aarch64-linux-gnu -fsanitize=memtag -march=armv8+memtag
qemu-aarch64 --cpu max -L /usr/aarch64-linux-gnu ./a.out

I see only: HWCAP_FP HWCAP_CRC32 HWCAP_ATOMICS
So no HWCAP2_BTI as well.

[Vitaly Buka (vitalybuka)]

Sorry, 0 7 8 should be "HWCAP2_DCPODP HWCAP2_FLAGM2 HWCAP2_FRINT"

[Richard Henderson (rth)]

Yep, there's a whole bunch that have been missed.

[Richard Henderson (rth)]

https://<email address hidden>/

This has missed 6.0, but should be acceptable to roll into 6.0.1.

[Vitaly Buka (vitalybuka)]

Thanks for the quick fix!

On Tue, Apr 27, 2021 at 2:55 PM Richard Henderson <
<email address hidden>> wrote:

>
> https://<email address hidden>/
>
> This has missed 6.0, but should be acceptable to roll into 6.0.1.
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1926044
>
> Title:
> QEMU-user doesn't report HWCAP2_MTE
>
> Status in QEMU:
> In Progress
>
> Bug description:
> Reproducible on ffa090bc56e73e287a63261e70ac02c0970be61a
>
> Host Debian 5.10.24 x86_64 GNU
>
> Configured with "configure --disable-system --enable-linux-user
> --static"
>
> This one works and prints "OK" as expected:
> clang tests/tcg/aarch64/mte-3.c -target aarch64-linux-gnu
> -fsanitize=memtag -march=armv8+memtag
> qemu-aarch64 --cpu max -L /usr/aarch64-linux-gnu ./a.out && echo OK
>
>
> This one fails and print "0":
> cat mytest.c
> #include <stdio.h>
> #include <sys/auxv.h>
>
> #ifndef HWCAP2_MTE
> #define HWCAP2_MTE (1 << 18)
> #endif
>
> int main(int ac, char **av)
> {
> printf("%d\n", (int)(getauxval(AT_HWCAP2) & HWCAP2_MTE));
> }
>
>
> clang mytest.c -target aarch64-linux-gnu -fsanitize=memtag
> -march=armv8+memtag
> qemu-aarch64 --cpu max -L /usr/aarch64-linux-gnu ./a.out
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/qemu/+bug/1926044/+subscriptions
>

[Thomas Huth (th-huth)]

Patch has been merged:
https://gitlab.com/qemu-project/qemu/-/commit/68948d18224b93361e28